Method of treating fibrous or filamentary material



P 1970 F. w.J. KARRER T L 3,528,

METHOD OF TREATING FIBROUS OR FILAMENTARY MATERIAL Filed March 25, 19682 Sheets-Sheet 1 STEAM I N VEN TOR 5.

FRIEDRICH WILHELM JOHANN KARRER, ALBERTQ PEDRETTI the r Sept. 15, 1970w, J, KARRER ET AL 1 3,528,180

- METHOD 0F TREATING FIBROUS OR FILAMENTARY MATERIAL Filed March 25,1968 2 Sheets-Sheet 2 BLEACH 0 N 3% N Lu W m N V M M: J D. g Qa m a: 2 23 g I\ ''z\ m E M 1 Q2 $1 IE 3 :3 u u N a a u O.

z\ k us 1 N v a N E: 9 4 M a n '45 N e I G :3 m g Q g N s I m a 3 T h asLg a INVENTORS.

FRIEDRICH WILHELMI JOHANN KARRER ALBERTO PEDRETTI their uropmsrs UnitedStates Patent 3,528,180 METHOD OF TREATING FIBROUS 0R FILAMENTARYMATERIAL Friedrich Wilhelm Johann Karrer, Strandvagen 37, Stockholm 0,Sweden, and Alberto Pedretti, Via Chelini 9, Rome, Italy Filed Mar. 25,1968, Ser. No. 715,782 Claims priority, application Sweden, Jan. 18,1968, 665/68 Int. Cl. F26b 3/00 US. Cl. 34-9 Claims ABSTRACT OF THEDISCLOSURE A method of treating fibrous or filamentary materials in aclosed container in which two chambers are formed and the onlycommuniction between the chambers is through the material. The materialis first treated with one or more liquid treating agents, such as dye,bleach, and wash, and is then dried. The drying procedure is composed ofan initial phase in which both air and steam are simultaneously passedthrough the material by establishing a pressure difference between thetwo chambers, the air and steam being introduced in a proportion suchthat a minimum amount of steam leaves the downstream side of thematerial and the major portion of the steam is condensed to transfer theheat of vaporization thereof into the material. The air serves both tomechanically expel moisture from the material and as a condensingassistant for the transfer of heat. When the material has been preheatedand mechanically dried to a maximum practical degree, further drying isaccomplished substantially by vaporization of moisture from the materialby passing hot air through it. In the later phases of the dryingprocedure, a small amount of steam may also be introduced with the hotair to add heat and thereby provide a greater rate of vaporization.

BACKGROUND OF THE INVENTION This invention relates to a method oftreating fibrous or filamentary materials, particularly textilematerials in the form of a spool or roll, such as a cross-wound spool ofyarn or a roll of fabric or randomly distributed fibers.

There are many specific techniques for treating rolls or spools oftextile materials with liquids, particularly dyeing and bleachingtreatments. After these processes the material must be dried, andparticular problems are encountered in obtaining rapid, efiicient, lowcost drying. A number of previously proposed techniques for drying rollsor spools of textile materials employ containers which are formed withtwo chambers and in which the material is disposed in such a way as tocommunicate the two chambers solely across the material. For example,the container structure may include perforated tubular elementsconstituting one chamber in the container and receiving the rolls orspools in surrounding relation. The external surfaces of the spools arethus exposed to the other chamber in the container, and communicationbetween the two chambers is solely through the material wound on therolls or spools.

The material has conventionally been dried by passing a gaseous dryingmedium through it. The techniques in this regard have varied. Forexample, one drying procedure op erates under relatively high pressure,say five atmospheres, and uses superheated steam as a drying mediumduring the initial phase of the drying procedure and heated air in thelater stages. Other methods use heated air alone and operate at variousrates and under various conditions to evaporate moisture. Some of thespecific techniques previously proposed have provided reasonably goodresults,

3,528,180 Patented Sept. 15, 1970 but they require considerable amountsof energy in the form of heat and pressure and therefore tend to becostly to carry out. Moreover, the high temperatures, particularly inclosed circuit systems, can adversely affect various components of theequipment, notably compressors, particularly where the compressors arehandling superheated steam. In any case, the procedures heretoforeproposed and used have frequently involved passing considerablequantities of air or steam through the material without efficientutilization of the heat content of these media, thereby considerablyreducing the efiiciency of energy utilization. For example, where steamis used in the drying process, only a relatively minor proportion of theheat content of the steam is transferred to the material to assist inremoving moisture from the material, the major portion of the steampassing through the material and being lost or conducted elsewhere forsome other use. Moreover, in a closed circuit system, the condensor doesnot remove all of the vapor particles so that the drying air is highlymoist and its ability to receive moisture from the material iscorrespondingly impaired.

SUMMARY OF THE INVENTION There is provided, in accordance with theinvention, a novel and improved method of treating fibrous andfilamentary materials, and particularly a method of drying the materialsafter a liquid treating process. The method provides substantialimprovements in the efliciency of the drying procedure as compared tothose previously proposed or used.

More particularly, the method is carried out utilizing a container whichis composed of two chambers and in which the material forms the onlypath of communication between the two chambers. Preferably, both theliquid treatment and the drying of the material are accomplished in thesame container utilizing a single compressor for establishing pressuredifferences between the chambers. The liquid treatment is accomplishedby reducing the pressure in the container first to draw air out of thematerial and then to suck the liquid treating medium into the containerthrough the material. The liquid treating material can also be pumpedback and forth between the chambers repeatedly across the material usinga circulation system, and can ultimately be expelled from the vessel bypositive pressure from the compressor, followed by applying vacuum tosuck out any remaining liquid.

After the liquid treatment phase, the material is dried, according tothe invention, by introducing both steam and air into one of thechambers during at least part of the procedure and causing the air andsteam to pass through the material by establishing and maintaining apressure difference between the two chambers. During the initial phasesof drying when the material is saturated and at the temperature of thelast liquid treatment (usually a cold water wash), the air and steam arepassed across the material to expel the moisture from it by primarilymechanical action and to heat the material so that further drying byvaporization of the moisture is facilitated. In the later stages ofdrying where the moisture is removed from the material by vaporization,it is desirable to continue to use both steam and air, the steam,however, being introduced in relatively small amounts to add heat to thematerial to assist in vaporizing the moisture.

Wherever both air and steam are simultaneously utilized in the dryingprocedure, the steam is introduced in only relatively small amounts as asource of heat, the major constituent of the drying medium being air.During the initial phase of drying, the steam is preferabl kept at alevel such that substantially all of the steam is condensed in thecontainer and a minimum amount leaves the downstream side of thematerial. Thus, the heat of vaporization of the steam is transferredinto the material to increase its temperature to slightly above theboiling point under the existing pressure conditions. The air serves asa carrier for the steam, aids in condensing the steam to recover heatfrom it, and is a recipient of and carrier for the vapor evolved fromthe material.

In the initial stage of the drying procedure, according to theinvention, it is preferable to employ a relatively cold air, such as airdrawn directly from the atmosphere. In combining with the steam in thecontainer, and particularly in the material, the relatively cool airactsas a condensing agent for the steam and provides for recovery of theheat of vaporization from the steam and heat transfer into the materialfor rapid preheating. The heating of the moisture in the material alsoreduces its viscosity and facilitates its removal.

In the final stage of the drying procedure, i.e., the part of the dryingprocedure after the moisture in the material has begun to boil under theprevailing conditions, hot air, preferably obtained by preheating airdrawn directly from the atmosphere, and preferably a small amount ofsteam, are used. The final stage of drying may also use hot air alone,i.e., without steam. The temperature of the air should be high enoughthat the steam does not condense in the chamber during the later dryingstages.

The air and steam, or where employed, air alone are preferably drawnthrough the material during the entire drying process by reducing thepressure in the chamber on the downstream side of the material to belowatmospheric. The reduced pressure in the downstream chamber should bekept sufiiciently low during the final stage that the moisture in thematerial boils. Thus the moisture is removed from the material primarilyby boiling. The pressure in the upstream chamber is maintained at ahigher level to cause transfer of heat to the material to enable thedrying thereof to take place. The pressure in the upstream side isdesirably just slightly less than atmospheric.

A particular advantage of the treating method of the invention is thatit is well suited for effecting drying in the same apparatus as used fora preceding liquid treatment of the fibrous or filamentary material, forinstance, dyeing or bleaching, particularly when, for the purpose ofhastening the said treatment, there is connection to a vacuum pump forevacuating the container. A plant in which the treatment apparatus isconnected to a pump unit functioning at different times as a compressorand vacuum pump is particularly suited to such a process, the suctionand pressure sides of the pump being alternately brought into connectionwith the treatment apparatus for providing the respective evacuation andrise in pressure.

Significant improvements in efficiency are obtained, particularly in theinitial preheating stage by utilizing to a maximum the heat input of thesteam in heating the material and in permitting only a minimum of steamto pass straight through the equipment. Because most of the steam iscondensed before the outfiowing gases reach the compressor unit, thevolume of fluids handled by the pump is substantially reduced ascompared to systems in which large quantities of steam pass through acompressor. Similar results are obtained in the later drying stages.Moreover, the compressor is not subjected to as severe heating. Thepower requirements for the compressor are similarly reduced by thereduced volume of fluids being handled.

DESCRIPTION OF THE DRAWINGS For a better understanding of the invention,reference may be made to the following description of an exemplaryembodiment, taken in conjunction with the figures of the accompanyingdrawings, in which:

FIG. 1 is a generally schematic illustration of a con- 4 tainer andassociated components useful in carrying out the method of theinvention, the view showing the container in cross-section; and

FIG. 2 is a schematic diagram of equipment for dyeing, bleaching anddrying a material according to an exemplary method.

DESCRIPTION OF EXEMPLARY EMBODIMENT Referring first to FIG. 1, theprincipal component of equipment for carrying out the method of theinvention is a well insulated container 1 for the material to betreated. Disposed in the lower portion of the container 1 is a closedinner chamber 3 which is connected to a vacuum pump 4 by a conduit 5.Material supports 6 in the form of perforated tubes open at the lowerend but closed at the top are mounted on the chamber 3 and communicatewith the interior of the Same. The material supports 6 are adapted tosupport crosswound spools 7, rolls or the like. The main chamber 8 ofthe container surrounding the spools 7 communicates with an inletconduit 9, a heat exchanger 10 heated, for example, by means of steambeing installed in the conduit, and with a steam line 11.

FIG. 2 shows diagrammatically a plant for dyeing, bleaching and dryingtextile material which incorporates the basic apparatus of FIG. 1. Theplant includes a container 21, which is substantially the same as thecontainer described in FIG. 1 and receives stationarily arrangedmaterial to be treated, e.g., cross-wound spools or fabric rolls, acontainer 22 for liquid dye, and a container 23 for bleaching liquid.

Connected to the treatment container 21, which may be heat insulated orprovided with a steam jacket for heating the material during and/orprior to the process, is a circulation system comprising a conduit 24,which is provided with a cut-off valve 25, a heat exchanger 26 adaptedto be heated by water or steam supplied through a conduit 27, a conduit28, a circulation pump 29 and its valve, and a conduit 30 provided witha valve 31. The conduit 30 is the counterpart of the conduit 5 in thecontainer of FIG. 1 and communicates with the chamber 3 and thence withthe interior of each material support tube 6 (see FIG. 1) in thecontainer 21, while the conduit 24 communicates with the main chamber 8surrounding the material.

The liquid dye container 22 is provided with an outlet 32 having acut-off valve 33 and a discharge conduit 34 by means of which liquid dyecan be transferred to the treatment container 21 by means of thecirculation system through a conduit 35 having a cut-off valve 36. Theliquid dye container 22 also communicates with the treatment container21 through a conduit 37 provided with a valve 38.

The bleaching liquid container 23 has an outlet 39 provided with acut-off valve 40. The bleaching liquid can be transferred from thecontainer 23 through a conduit 41 having a valve 42 and a conduit 43connected to the conduit 30. Further, connected to the conduit 43 is anoutlet conduit 44 provided with a cut-off valve 45 and a water supplyconduit 46 provided with a cut-off valve 47.

Also connected to the main chamber 8 of the container 21 is a conduit48, which is provided with a valve 49 and communicates with one branch51a of a 4-way valve 51. A second branch 51b of the valve 51 isconnected to the suction side of a compressor and vacuum pump unit 52through a conduit 53, and a third branch 51c communicates with thepressure side of the pump unit 52 via a conduit 55 which has awater-separator 54. The fourth branch 51d is an outlet conduit 56 forexhaust air and may lead to the atmosphere or to any suitable placewhere hot air might find use. The 4way valve 51 can be shifted so thatthe container 21 is placed in communication with the pressure side (theposition shown in FIG. 2) of the pump unit 52, or with its suction side.A conduit 59 provided with a cut-off valve 60 connects the conduit 30with the conduit 48. An air inlet conduit 50, equipped with a valve 50aand a heat exchanger 57, and a steam supply line 58 having a cut-offvalve 58a lead into the main chamber 8 (see FIG. 1) of the container 21.

The procedure employed to dye material using the equipment of FIG. 2begins after the material has been introduced into the container 21 byplacing the container in communication with the suction side of the pumpunit 52 by shifting the 4-way valve 51 to connect branches 51a and 51bso that the container is evacuated through lines 30, 59 and 53. At thispoint, all valves other than valve 60 are closed, the heat exchangersare shut 01f, and the pump 29 is not operating. When a maximum vacuum inthe container has been reached, dyeing liquid is drawn or sucked intothe treatment container 21 from the dye container 22 until the materialin the container 21 is completely covered with the liquid. The heatexchanger 26 is then started up and circulation by means of thecirculation pump 29 of dye through the material is begun. The 4-wayvalve 51 is shifted to the position shown in FIG. 2, and the valve 49opened so that the container 21 can be subjected to positive pressure.The positive pressure can be maintained during the whole of thecirculation process, or merely for a portion of the same. Further, incertain cases it may be suitable to subject the container 21 alternatelyto positive pressure and sub-pressure by shifting the valve 51appropriately.

On completion of the dyeing process and when the circulation has beenstopped, the used liquid dye can be removed through the conduits 30, 43and 44 by the aid of positive pressure in the container 21 or, if sodesired, returned to the container 22 through the conduit 37. Water forwashing the material can then be supplied from the conduit 46, by firstre-connecting the container 21 to the suction side of the pump unit 52and evacuating it, then admitting the water and finally pulling it outby vacuum and discharging it to the separator 54, from which it may beremoved. Alternatively, the water can be pushed out by positive pressurejust as the dye and bleach are (see above). The wash process is repeateduntil the material has been properly washed.

Bleaching is in principle effected in the same way as that describedabove, after bleaching liquid from the container 23 has been introducedinto the container 21 and surplus bleaching liquid returned, by means ofpositive pressure, to the container 23. The material may be heatedduring bleaching processes according to my patents U.S. Nos. 2,808,715and 2,959,047 by introducing steam and hot or cold air and drawing themthrough the material in the container 21 by suction from the unit 52.Air may be injected particularly in the case of hypochlorite bleaching,the carbon dioxide of the air hastening the bleaching process. Air canalso be injected on completion of the dyeing process to neutralizecertain pigments.

After completing the dyeing, washing and bleaching treatments, thedrying of the material is started by placing the container incommunication with the suction side of the compressor unit 52 throughthe conduit 59, valve 51 and conduit 53 by simultaneously introducingair and steam into the container through the conduits 50 and 58,respectively. The initial phase of the drying process is a mechanicaldewatering and preheating stage in which the air and steam are drawnthrough the material in a manner mechaniclly removing the major portionof the moisture in the then saturated material and in which thematerial, which is then usually at the temperature of the bleach, or dyeor a final wash, is raised to slightly above the boiling point for theconditions obtaining in the container. The proportion of air and steamis preferably established such that substantially all of the steam iscondensed in the material and will generally be between 1:1 and 15:1 byweight. The air may be relatively cool and desirably is drawn directlyfrom the atmosphere without any preconditioning, other than filtering.As the steam and air pass through the material, the steam is condensedby the air and the relatively cool material so that substantially all ofthe steam is condensed and its heat of vaporization is transferred intothe material. The optimum conditions, in general, exist when a minimumamount of steam is leaving the downstream side of the material. Thesteam is desirably superheated so that additional heat is introducedupon expansion in the container and so that minimum condensation occursin the chamber 8 prior to entry of the air and steam into the material.If chemical residues remain on the fibers, the condensing steam aids indissolving and washing them away, so that the previous Washing step canbe shortened.

The passage of the air and steam through the material is effected byreducing the pressure in the chamber 3 by means of the compressor unit52. The pressure in the chamber 3 may be on the order of 0.5 to 0.7 atm.The pressure in the main chamber 8 of the container will be somewhathigher due to the resistance of flow through the material, say on theorder of 0.1 to 0.3 atm. higher than in the chamber 3. Desirably, themain chamber is at or only slightly below atmospheric pressure.

The introduction of air and steam to mechanically dewater and to preheatthe material is continued until the temperature of the material has beenraised sufficiently so that a favorable condition for the furtherprocess is achieved. When this point has been reached, further drying isaccomplished by introducing hot air into the main chamber, preferablyalong with a minor amount of steam to add additional heat to thematerial as drying proceeds. Nevertheless, hot air alone may be usedfrom this point on, or steam may be introduced only periodically. Wheresteam is used, it is preferably superheated and is intro duced inproportions relative to the air introduced with it, ranging frompreferably about 1:10 to 1:100 by weight. The pressure conditions aremaintained substantially as in the preheating stage. The air used forfurther drying is drawn in through the inlet conduit 50 and is heated bythe heat exchanger 57, which is turned on at the point when hot air isto be used subsequently, to a temperature above the boiling point in thechamber but not so high as to damage the material. Where steam is used,it will be noted that the hot air does not permit condensation of thesteam in the container. Nonetheless, the steam will condense out in thevacuum pump. Its volume per unit heat input is small, and the vacuumpump can therefore be of lower capacity than if hot air alone were used.Drying with hot air is continued to completion of drying as indicated bythe temperature of the vaporladen air leaving the chamber 3.

A typical example of the drying process as applied to spools of cottonyarn is as follows: When drying begins, the yarn is saturated with washwater to about 200%. The suction side of the compressor unit 52 isbrought into communication with the chamber 3, as above, and theintroduction of air and steam into the main chamber of the container iscommenced. The proportion of air to steam is on the order of 7:1 byvolume, and the steam is superheated to 120 C. The compressor isoperated to provide a pressure of approximately 0.7 atm. in the chamber3 so that with a pressure of 0.3 atm. across the material the mainchamber in the container is at substantially atmospheric pressure. Themechanical dewatering and preheating of the yarn under these conditionstakes approximately five minutes, and completion ofthe initial stage ofdrying is indicated by a temperature of the vaporladen air leaving thechamber 3 of C. This temperature is indicative of a temperature on theoutside of the spools of about C.

At this point, the heat exchanger 57 is turned on so that the airconducted into the container is preheated. The temperature of the heatedair used during the remainder of the drying procedure should be slightlyover 100 C. During the later drying, a small amount of steam, say onepart to 50 parts air, superheated to say C. can be introducedsimultaneously with the air to add further heat to the material,although this is optional.

7 The drying of the material using hot air, and preferably a smallamount of steam is continued to completion, and it has been found totake on the order of one hour.

The above-described embodiment of the invention is intended to be merelyexemplary, and those skilled in the art will be able to make numerousvariations and modifications of it without departing from the spirit andscope of the invention.

We claim:

1. A method of treating fibrous or filamentary materials in a closedcontainer in which two chambers are formed and the only communicationbetween the chambers is through the material comprising as at least partof a drying procedure the steps of establishing and maintaining apressure difference between the chambers effective to conduct a gaseousdrying agent through the material, simultaneously introducing in theinitial stage of the drying procedure both air and steam into the higherpressure chamber partially to dry the material by primarily a mechanicalaction and to preheat the material to a temperature facilitating laterdrying primarily by vaporizing the moisture in the material, the air andsteam being introduced in a proportion such that a minimum amount ofsteam leaves the downstream side of the material and the major portionof the steam is condensed in the material thereby to transfer the heatof vaporization thereof into the material, the steam being superheatedto an extent such that minimum condensation takes place in the chamberprior to entry into the material on the upstream side thereof, andthereafter in the later stages of drying introducing heated air into thesaid one chamber to further dry the material primarily by vaporizing themoisture therein.

2. A method according to claim 1 wherein the proportion by weight of airto steam introduced during the said initial stage of drying is betweenabout 1:1 and :1.

3. A method according to claim 1 wherein the steam introduced during theinitial stage of the drying procedure is superheated to a temperature ofabout 120 C.

4. A method according to claim 1 wherein the initial stage of the dryingprocedure in which the drying of the material is primarily by amechanical action is carried out until the temperature of thevapor-laden air measured in the downstream chamber of the container,relative to the flow of gaseous drying agent through the material,reaches a value of about C.

5. A method according to claim 1 wherein the air introduced in the saidlater stages of drying is introduced at a temperature above C.

6. A method according to claim 1 wherein the proportions of air to steamintroduced in the later stages of the drying procedure is from about10:1 to 100:1 by weight.

7. A method according to claim 1 wherein the air introduced during thesaid initial stage of the drying procedure is at a temperaturesubstantially below the temperature of the steam, thereby to aid incondensing the steam.

8. A method according to claim 1 wherein the air is introduced duringboth of said stages of the drying procedure at atmospheric pressure, andwherein the pressure difference between the chambers is created byreducing the pressure in the other one of said chambers to belowatmospheric pressure.

9. A method according to claim 1 wherein steam is introducedsimultaneously with air during at least a part of the said later stagesof the drying procedure to add heat to the material to aid in thevaporization of the moisture therefrom.

10. A method according to claim 1 further comprising the step oftreating the material with a liquid prior to the drying procedure byconducting the liquid between the chambers through the material.

References Cited UNITED STATES PATENTS 630,293 8/ 1899 Maertens 3415 XFOREIGN PATENTS 494,838 7/1950 Belgium.

JOHN J. CAMBY, Primary Examiner US. Cl. X.R.

